A narrative review of the clinical approach to subsolid pulmonary nodules

Abstract

Background and Objective The widespread use of chest computed tomography (CT) for lung cancer screening has led to increased detection of subsolid pulmonary nodules. The management of subsolid nodules (SSNs) is challenging since they are likely to grow slowly and a long-term follow-up is needed. In this review, we discuss the characteristics, natural history, genetic features, surveillance, and management of SSNs. Methods PubMed and Google Scholar were searched to identify relevant articles published in English between January 1998 and December 2022 using the following keywords: “subsolid nodule”, “ground-glass nodule (GGN)”, and “part-solid nodule (PSN)”. Key Content and Findings The differential diagnosis of SSNs includes transient inflammatory lesions, focal fibrosis, and premalignant or malignant lesions. Long-term CT surveillance follow-up is needed to manage SSNs that persist for >3 months. Although most SSNs have an indolent clinical course, PSNs may have a more aggressive clinical course than pure GGNs. The proportion of growth and the time to grow is higher and shorter in PSN than pure GGN. In lung adenocarcinoma manifesting as SSNs, EGFR mutations were the major driver mutations. Guidelines are available for the management of incidentally detected and screening-detected SSNs. The size, solidity, location, and number of SSNs are important factors in determining the need for surveillance and surgical resection, as well as the interval of follow-up. Positron emission tomography/CT and brain magnetic resonance imaging (MRI) are not recommended for the diagnosis of SSNs, especially for pure GGNs. Periodic CT surveillance and lung-sparing surgery are the main strategies for the management of persistent SSNs. Nonsurgical treatment options for persistent SSNs include stereotactic body radiotherapy (SBRT) and radiofrequency ablation (RFA). For multifocal SSNs, the timing of repeated CT scans and the need for surgical treatment are decided based on the most dominant SSN(s). Conclusions The SSN is a heterogeneous disease and a personalized medicine approach is required in the future. Future studies of SSNs should focus on their natural history, optimal follow-up duration, genetic features, and surgical and nonsurgical treatments to improve the corresponding clinical management. All these efforts will lead to the personalized medicine approach for the SSNs.

Synchronous Computed Tomography-Guided Percutaneous Transthoracic Needle Biopsy and Microwave Ablation for Highly Suspicious Malignant Pulmonary Ground-Glass Nodules

“…Despite that PTNB has a high accuracy for differentiating malignant from benign lung nodules, the diagnosis for GGN remains challenging because of the greater difficulty of locating the lesion and the higher likelihood of hemorrhage upon biopsy [34], which could result in a lower diagnostic accuracy than that of solid nodules. Due to the low risk of metastasis of GGNs and the above-mentioned major limitations of PTNB for GGN, surgical resection for peripheral GGN has been the preferred option as compared with PTNB [35]. However, some patients with compromised cardiopulmonary function would be generally ineligible for surgical resection, among whom minimally invasive therapies such as radiotherapy and LTA may be preferred.…”

The Application of online medicine in the diagnosis and treatment of pulmonary nodules in thoracic surgery (Preprint)

“…Pulmonary nodules include benign and malignant nodules. Solitary benign pulmonary nodules are mostly granulomatous inflammation, hamartoma, etc., while malignant pulmonary nodules are more insidious in the early stages of onset and are mostly primary bronchogenic carcinoma 13,14 .…”

Subsolid pulmonary nodules: why not “watch and wait”?

“…PSNs are lesions with recognized aggressiveness and metastatic potential, especially when their solid component is larger than 5–6 mm ( 4 ). In general, these lesions are managed more aggressively, both from a diagnostic and therapeutic perspective ( 5 ). Initially, percutaneous CT-guided biopsy is not recommended since the vast majority are adenocarcinomas, there is a significant sampling error risk when attempting percutaneous biopsies (given the difficulty in targeting both solid/invasive and ground-glass/non-invasive components), and that certain pathologic diagnoses (such as adenocarcinoma in situ , minimally invasive adenocarcinoma…) cannot be made in small specimens obtained percutaneously ( 6 - 9 ).…”

“…Management of pure GGNs and PSNs with a small solid component (less than 5–6 mm) is more variable and controversial ( 5 ). Although some clinicians prefer to use an aggressive/invasive strategy in this setting as well, a more thoughtful “watch and wait” approach (always considering different factors beforehand) may be feasible due to their indolent course and good prognosis ( 3 , 10 - 13 ).…”